World War Two: Day of Infamy, 7 December 1941

FIRST AIR FLEET: During the Strike Force’s run south, because of the rough seas, it was still not known whether the planes could be launched on schedule. At 0500, reconnaissance floatplanes were catapulted from the heavy cruiser Tone and Chikuma to determine whether conditions were still favorable for the raid. (Reports were, in fact, received from them just prior to the attack, marking ship targets.) An hour later, it was decided to launch the first strike at once, because it was feared that the pitching carrier decks would make the launching operation take longer than planned. Yamamoto believed that the formal declaration of war would be delivered to the U. S. Secretary of State Cordell Hull by Ambassador Kichisaburo Nomura and Special Envoy Saburo Kurusu, at 0800 Hawaiian time; he had issued strict orders that the raid should not take place until after war had been declared–preferably at least thirty minutes afterward. He could not afford a much longer wait, because then the secrecy of the air assault would be endangered. If Nagumo began to launch at 0530 instead of 0600, and if the launch were executed in an ordinary amount of time the attack would occur at the moment of the declaration. (As it turned out, incredible inefficiency at the Japanese Embassy in Washington delayed the declaration until well after 0830 Hawaiian time.)

The six carriers turned north into the wind, and the launch went smoothly, despite the heavy seas. By 0615 Hawaiian time all 183 aircraft of the first strike wave, led by Commander Mitsuo Fuchida, a twenty-five year veteran of naval aviation, were on their way. From the six carriers came 49 high-level bombers, each carrying one 1,6000 pound armor piercing modified naval shell, 40 more planes carrying the specially designed shallow-running torpedoes, and 51 dive bombers armed with 500-pound bombs. Flying as a cover were 43 Zero’s.

The objectives of the combined air fleet were two fold, with all targets well-assigned. One group of dive-bombers would break into sections in order to neutralize the army, navy and marine airfields in the first five minutes; the remaining planes’ objective was the U. S. Fleet. If complete surprise at Pearl Harbor was achieved, Commander Fuchida would signal to that effect. Then the U.S. ships were to be destroyed as follows: first, the torpedo planes would attack, with battleships and carriers as primary targets, and then high-level and dive bombers would attack other targets of opportunity among the fleet. If complete surprise had not been achieved, Fuchida would give a different signal and the attack would proceed in reverse order: the Japanese would send their bombers in first, hoping that in the confusion of the attack, American gunners would be so preoccupied that the torpedo planes could slip in unnoticed, at water level. Hickam, Wheeler, Kaneohe, Ewa, Bellows , and Ford Island fields were dive-bombed at 0755. At 0800, Zero’s strafed these fields to destroy undamaged planes remaining on the ground or to shoot down any planes managing to get a loft.

The sight that met the eyes of those flyers ordered to make the direct attack on the American naval units in Pearl Harbor was awe-inspiring, despite the hours of drill at the mock-up tables and at Kagoshima Bay. Lying below them in the early morning sunlight, only partially obscured here and there by shreds of clouds from an earlier light rainfall, the Japanese saw some ninety ships of the U.S. fleet spread out before them. Seven battleships were moored close together in battleship row, and the Pennsylvania was in No. 1 drydock. Scattered at their various berths were the other ships of the fleet; two heavy cruisers, six light cruisers, twenty-nine destroyers, three seaplane tenders, five submarines, ten minesweepers, nine mine layers and various auxiliary craft. But the instant before the attack, the Japanese saw that that there indeed were no aircraft carriers present; although the flyers were disappointed, they did not yet know how fateful to the Japanese war effort this turn of events would be.

As so often happens in the excitement of battle, the agreed upon order of attack fell into shambles. The “complete surprise” signal of Fuchida was virtually ignored. At 0755, the torpedo planes and the high-level and dive bombers all went in together, neither group waiting for the other. Having achieved complete surprise, they met no initial anti-aircraft fire; it then built up only to a negligible response. For the first fifteen minutes, Pearl harbor was an arena of wave-skimming torpedo planes, plunging dive bombers, and high-level bombers, small specks in the sky–all discharging their lethal cargoes. At 0810, an enormous explosion in the Arizona sent a column of red-cored black smoke hurtling into the sky. One of eight hits by 1,600 pound bombs had penetrated he forward power magazine. She rose form the water, broke in half, and settled back–in an instant, she had become a total wreck. Other warships were sinking, capsizing or a fire. Similar success was achieved in attacks on the airfields, so that American air power was almost completely neutralized within a few minutes.

Slowly American counter-fire, at first wildly inaccurate, began to score. But the first wave of attack continued, with planes seeking new targets of opportunity or re-bombing ships that had already been crippled. At 0830, a lull developed, but Fuchida rallied his planes and the attack regained its intensity, until the planes ammunition started to give out and their gas began to run low. The first strike, although out of formation, then began to return to their carriers.

The carriers had already launched the second strike of 167 planes at 0715, with the same mixture of plane types and tactical assignments as before. This wave hit Pearl Harbor at 0915. It met a greater amount of hostile fire, and , while the attack was pressed home against fleet ships with the same intensity, it did little additional damage. Further attacks were made on Hickam Field, Ford Island, and Kaneohe air base, also with only minor results. By 1000, the second wave withdrew. The attack was over, although neither side yet realized it.

The damage was finally officially tabulated as follows: Battleships: Arizona, Blown up with a loss of over 1,000 lives—Oklahoma; capsized small part of hull above water— California; “sand gradually for three or four days”…”quarterdeck under twelve feet of water”—Nevada; beached opposite Hospital Point, wrecked condition—West Virginia; sunk at berth—Maryland; moderately damaged—Tennessee; seriously damaged to moderate — Pennsylvania; considerable damage in drydock—Utah; capsied at berth

Light Cruisers: Raleigh, Helena, Honolulu (moderately damaged)

Destroyers: Cassin and Downes ; (in drydock No. 1) severely damaged–Shaw; bow blown off (floating drydock)

Others: Repair ship Vestal alongside Arizona (beached)—seaplane tender Curtiss; badly damaged by crashing plane and 500 lb. bomb—minelayer Oglala; capsized…

American losses in military aircraft were also staggering, 188 planes destroyed 159 badly damaged only 43 still operational after attack. Military personnel losses were 2,403 killed, 1,178 wounded. Japanese losses were twenty-nine planes (15 dive-bombers & high-level bombers; 5 torpedo planes; 9 escort fighters)

SOURCE: Battle History of the Imperial Japanese Navy (1941-45); BY: Paul S. Dull

For the first half of 1941 the military strategy and preparations of the United States were aimed toward belligerent participation in the Atlantic war and maintenance in the Pacific of a defensive posture based on Alaska, Hawaii, and Panama. Then, during July, Pacific strategy and preparations began a rapid shift that profoundly affected the outlook and thinking of American commanders both in Washington and in Hawaii. Through decoded intercepts, Washington knew early in the month that Japan had decided upon further aggression to the south. In the light of this knowledge, during the last week of July the United States decided to try to defend the Philippines in the event of war with Japan, and at the same time it applied stringent economic sanctions against Japan which were intended to deter the Japanese but which actually had the opposite effect. During August and September, the War Department developed an entirely new concept for defending the Philippines and checking a Japanese sweep southward. It now planned to station large numbers of Army heavy bombers (B-17’s) in the Philippines. This plan in turn required the quick preparation of intermediate supporting bases at Midway and Wake Islands along the direct air route from Hawaii to Manila and similar preparations as soon as possible along a secondary route to the southwest toward Australia.

Everyone recognized that these plans and preparations of late 1941 for projecting American military power toward and into the Far East could not become effective before early 1942, but no one either in Washington or in Hawaii gave much thought to calculating what should be done in case the Japanese chose to strike before then. In particular, the danger of a Japanese carrier-based air raid on Oahu, which had been recognized as very real in early 1941, all but ceased to be a matter of immediate concern; whereas, with the increasing likelihood of war with Japan, the danger of sabotage on Oahu loomed ever larger, not only in the thinking of the local Army and Navy commanders and their staffs, but also in Washington. As General Marshall put it, in testimony soon after the event, “I fully anticipated a terrific effort to cripple everything out there by sabotage“; and at the same time he acknowledged that to him the carrier attack had been an almost totally unexpected blow.

The Approach to War

The first warning to the Hawaiian Department that Japan had determined upon a new course of aggressive action went out from the War Department on 7 July 1941, though in milder language than the alerts flashed to Alaska and Panama four days earlier.  Later in the month, and six hours before the new economic sanctions against Japan became effective, General Short received his second warning, this time with advice that, while no immediate military retaliation by Japan was anticipated, the Hawaiian commander should take “appropriate precautionary measures.”  The general did so by ordering a full alert of his forces, in marked contrast to the lesser action taken by him four months later. His chief of staff explained to the local press that Army forces were “taking to the field for a ten-day maneuver period.” After several days the general called off the “maneuvers,” but he left Army guards on 24-hour watch at military and public utility installations, highway bridges, and along the Honolulu waterfront.

The first warning to Hawaii that Japan might soon resort to military action against the United States was sent by the Navy to its fleet commanders, including Admiral Kimmel, on 16 October. Because the Army staff in Washington disagreed with the Navy’s alarm, the War Department sent a supplementary message to the Far East commander, General Douglas MacArthur, and to General Short, advising them that although “tension between United States and Japan remains strained . . . no abrupt change in Japanese foreign policy appears imminent.” In short, the War Department did not think that Japan might be on the verge of attacking the United States. Under the circumstances General Short saw no need to do any more than what he was already doing. Vital installations had remained under guard against sabotage since July, and he “simply cautioned people who were responsible for that guarding to be unusually careful.” No further official word about the prospects of war with Japan reached General Short directly from the War Department until 27 November, and it came then only after action by the Japanese and American Governments that made an early outbreak of war all but certain. Of course the general by reading the local newspapers could and presumably did learn unofficially a good deal about the tense negotiations with Japanese envoys in Washington, since the local press reported these negotiations very fully; and by 27 November this reporting included an accurate prediction of an impending rupture and of Japanese warlike moves in the offing.

On the eve of conflict the Honolulu press also reflected the opinion widely held in Washington that Japan was too weak to pose a really serious threat to the United States. As of 21 November the Secretary of the Interior, for one, was urging President Roosevelt to launch an immediate attack on Japan’s naval forces in their home waters, in order to destroy them and thus release American naval strength for full duty in the Atlantic at an early date. In September a War Department G-2 estimate of the Japanese Navy had paid it much higher respect; but of Japanese aircraft performance in China it rather condescendingly noted: “Plane design has lagged, but lack of formidable opposition has left them undisputed air superiority.” A similar assumption lay behind General Arnold’s remark on 26 November that the Japanese had no seaborne aircraft that could catch one of the new Army B-24 heavy bombers, which with light loads could fly 290 miles per hour at 15,000 feet. He was wrong, as the Japanese Zeros that appeared over Pearl Harbor two weeks later were soon to prove. About 28 November G-2 estimated that Japan was then “completely extended militarily and economically” and thus was “momentarily unable to concentrate anywhere a military striking force sufficient to ensure victory”; and G-2 followed this estimate with a prediction on 5 December 1941 that for the next four months Germany would “remain the only power capable of launching large scale strategic offensives.”

If not reflecting informed opinion, the Honolulu Advertiser appears at least to have been in tune with it in stating in a lead editorial of 3 December 1941:..Unless there is an immediate and complete reversal of Tokyo policy, the die is cast. Japan and America will travel down the road to war. Such a course should be sad for Japan to contemplate. She is the most vulnerable nation in the world to attack and blockade. She is without natural resources. Four years of war have already left deep scars. She has a navy, but no air arm to support it….In fact Japan had ten aircraft carriers, to match the three then available in Pacific waters to the United States Navy and its associates.

As late as Friday, 21 November, President Roosevelt appears still to have been very doubtful about the intention of the Japanese to go to war, and reluctant to press matters with Japan. After lunching with the President, Secretary of the Interior Harold L. Ickes recorded Mr. Roosevelt’s remarks, “he wished he knew whether Japan was playing poker or not,” and “he was not sure whether or not Japan had a gun up its sleeve.” In fact, Japan had several guns, and the one that would soon go off with the biggest bang was the Japanese Navy’s Striking Force then completing its assembly in Tankan Bay in the southern Kurils, preparatory to a dash across the Pacific toward Hawaii.

By Monday afternoon, 24 November, the President and Secretary of State Hull had come to the conclusion that there was little remaining hope for a fruitful outcome of the negotiations. With Mr. Roosevelt’s approval Admiral Stark and General Marshall thereupon drafted a joint dispatch to the senior Army and Navy commanders in the Philippines, which went out as a Navy message not only to the Philippine but also to other Navy commanders, including Admiral Kimmel. The message warned of “a surprise aggressive movement in any direction” by Japanese forces, “including an attack on the Philippines or Guam;” and it requested its action addressees (among them, Admiral Kimmel) to inform the senior Army officer in their respective areas.

When the next and better known warnings of 27 November went out, the Army and Navy chiefs in Washington knew that war was all but certain, and probably imminent, although they had not been consulted about, nor even shown, the answer given to the Japanese envoys the preceding afternoon. Their concern and that of their staffs remained the Philippines; the War Department drafted its message of 27 November as a warning to General Douglas MacArthur, and phrased it to fit his peculiar circumstances. Unfortunately, only slightly modified versions that did not take local circumstances so carefully into account were sent to the other principal Army commanders in the Pacific area, in Panama, on the west coast, and in Hawaii. General Short’s version read: Negotiations with Japan appear to be terminated to all practical purposes with only the barest possibilities that the Japanese Government might come back and offer to continue. Japanese future action unpredictable but hostile action possible at any moment. If hostilities cannot, repeat cannot, be avoided, the United States desires that Japan commit the first overt act. This policy should not, repeat not, be construed as restricting you to a course of action that might jeopardize your defense. Prior to hostile Japanese action, you are directed to undertake such reconnaissance and other measures as you deem necessary but these measures should be carried out so as not, repeat not, to alarm the civil population or disclose intent. Report measures taken. Should hostilities occur, you will carry out the tasks assigned in Rainbow 5 as far as they pertain to Japan. Limit dissemination of this highly secret information to minimum essential officers.

Whereas the directive of General MacArthur to undertake reconnaissance was a sensible one, since that was at least partially his responsibility, it was not applicable to General Short’s situation, for seaward reconnaissance to any meaningful distance was recognized in Hawaii as strictly the Navy’s business. Furthermore, the clear instruction for action to General MacArthur, “you are directed to undertake such reconnaissance and other measures as you deem necessary,” was qualified in the other messages by the added phrase, “but these measures should be carried out so as not to alarm civil population or disclose intent.” But almost anything that General Short might do on Oahu was bound to be observed; as his predecessor, General Herron, subsequently remarked, “Hawaii, or Pearl Harbor, is a goldfish bowl.” The first draft of the Hawaiian message had also included a specific warning about subversion; but after argument this warning went out as a separate and almost simultaneous G-2 message, in these terms: “Japanese negotiations have come to practical stalemate. Hostilities may ensue. Subversive activities may be expected. Inform commanding general and Chief of Staff only.”

Within half an hour after receiving the first message, and before he saw the second, General Short (after consulting with his Chief of Staff only) sent his report of action taken: “Report department alerted to prevent sabotage. Liaison with Navy.” The parallel Navy Department message of 27 November to Admiral Kimmel, more definite in its warning than the War Department’s, reached Hawaii some time later in the day. Subsequently, General Short remembered seeing it (or at least a paraphrase of it), although he could not remember that it had in any way influenced his own course of action, despite its clear opening phrases: “This dispatch is to be considered a war warning. Negotiations with Japan . . . have ceased and an aggressive move by Japan is expected within the next few days.” Possibly the edge of these phrases was blunted for the Hawaiian commanders by the last sentence of the message, which implied that sabotage was now the worst that need be expected as far east as Guam and Samoa.

The next day, 28 November, the Hawaiian Department received two more messages from Washington, one addressed to General Short and the other through him to his air commander, both of them emphasizing the need for the most careful precautions against sabotage and other subversive activities. The general assumed these messages were follow-up replies to his terse report of the 27th. He answered the first of the new messages promptly and in detail, and this reply reached General Marshall’s office on 1 December. Since Washington made no comment on either of his reports, and gave him no further guidance about the impending crisis before the great blow fell, the general assumed also that the War Department approved his course of action.

General Short’s action had been to order an Alert No. 1, as defined in a new Standing Operating Procedure dated 5 November 1941. This alert assumed increased danger of sabotage and internal unrest, but no threat from without. Under it the Army, in General Short’s words, “put out a lot of additional guards and checked on everything,” and for the two infantry divisions this meant keeping thirty officers and 1,012 enlisted men on guard and patrol duty. The Hawaiian Air Force was ordered to concentrate planes so that they could be guarded more easily, and these orders were as easily executed since that was the usual practice at Hickam and Wheeler Fields anyway. The only deviation from procedures prescribed under Alert No. 1 was an order directing the operation of the new Army radar machines between four and seven each morning-the most likely period for a carrier strike, according to previous studies. On 28 November the local press explained, “The entire Hawaiian Department was ordered on a ‘routine training alert’ last night.”

Why General Short did not alert his command more fully was to become the subject of long questioning after the Japanese attacked. The new Standard Operating Procedure had prescribed two higher alerts: under No. 2, against a threat of air and surface bombardment, all coastal and air defenses, including antiaircraft guns, were to be ready for action; under No. 3, against a threat of invasion as well, all Army defenders were to occupy battle positions. When first questioned, General Short said he ordered Alert No. 1 for three reasons: first, he thought there was a “strong possibility” of sabotage, and he feared sabotage more than anything else; second, he had no information about any danger of external attack; and third, either No. 2 or No. 3 would interfere very seriously with training-“it was impossible to do any orderly training with them on.”

Before the warnings from Washington came in on 27 November, General Short had been in conference for three hours during the morning with Admiral Kimmel, Admiral Bloch, and members of their staffs, discussing a Washington plan for reinforcing Midway and Wake Islands by sending out fifty of the most modern Army pursuit planes then on Oahu. A proposal that the Hawaiian Department should part with half of its effective pursuit strength for even a limited period must itself have been an indication to General Short, as it was to Admiral Kimmel, that Washington had no inkling of any Japanese plan to attack Oahu. For local warning of such an attack the general was completely dependent on the Navy. During the conference on the 27th Admiral Kimmel turned to his War Plans officer, Captain Charles H. McMorris, and asked specifically what the chances of a surprise raid on Oahu were, and the answer was “none.” No one of the other Navy officials present challenged this judgment, and General Short saw no reason to question it. Both he and his naval colleagues were also heavily influenced by the knowledge that Japan could not attack Oahu with land-based planes, and by the continuing assumption that the Japanese would not risk a carrier strike as long as the bulk of the Pacific Fleet was in or west of Hawaiian waters.

The proposal to send Army pursuit planes to Midway and Wake was only one of several measures planned or in preparation for sending Army reinforcements out of Oahu to the westward and southwestward, in anticipation of Japanese action. On 27 November General Short informed Admiral Bloch that the Army could not spare any 500-pound bombs with which to stock Midway and Wake; and even if that had been possible, the Army had no heavy bombers available to operate from them in an emergency-while the Hawaiian Department had six B-17’s in commission, all available and trained B-17 crews were engaged in ferrying heavy bombers to the Philippines. On 29 November the War Department notified the general that it had assumed responsibility for defending Christmas and Canton Islands on the new air ferry route to Australia and directed him to prepare small task forces for dispatch to these islands as soon as possible. Meanwhile, the flow of B-17’s from California through Hawaii to the Philippines continued; all of them came into Oahu unarmed, and it was General Short’s responsibility to- see to it that they were made combat-ready before flying westward.

All these factors helped to influence General Short’s decision to order and maintain a No. I alert only; and he must also have been influenced by knowledge that his air defense system was not ready to operate and that he could not spot many of the Army’s antiaircraft guns in their assigned field positions without provoking protests from powerful civilian interests on Oahu.

The Navy commanders had no more prescience than General Short in foreseeing what was about to happen. The Navy was already operating under procedures similar to those under the Army’s No. 1 alert; and the only new precaution ordered locally after the warning of the 27th was a careful surface patrol of Hawaiian waters against submarine attack. The Navy had about fifty long-range patrol planes with which it could have instituted distant reconnaissance from Oahu; but after careful reflection Admiral Kimmel decided his best course was “to bend every effort towards getting the patrol planes ready for unlimited war operations” rather than “to expend their efforts in partial and ineffective peace-time searches.” In consequence, when the attack came, the Navy had only three of its Oahu-based patrol planes in the air. And these were fleet planes, since none of the 108 aircraft specifically allotted by the Navy to Hawaii for distant reconnaissance was due to arrive for another year.

Between 27 November and 7 December 1941 neither the Army nor the Navy made an effort to invoke any of the plans for unity of command and joint operations so carefully drawn earlier in the year. Despite General Short’s personal conferences with Navy opposites on 27 November and on several other occasions during the succeeding ten days, an almost perfect insulation continued to exist between the local defense preparations of the two services (the conferences being about new defense measures to the westward). On this score, there can be no exception to what the majority of the Congressional Pearl Harbor Joint Committee had to say in 1946: “It can fairly be concluded that there was a complete failure in Hawaii of effective Army-Navy liaison during the critical period and no integration of Army and Navy facilities and efforts for defense. Neither of the responsible commanders really knew what the other was doing with respect to essential military activities.” Perhaps the most significant explanation of the almost complete absence of effective co-operation between the Army and Navy in local defense matters is the one pointed out by the Army and Navy Pearl Harbor investigating boards, that in Hawaii “no one in authority appreciated the danger to which Pearl Harbor was exposed and consequently the Army and Navy commanders . . . were preoccupied with training activities to the exclusion of adequate alertness against attack.”

In any event Army and Navy business on Oahu proceeded almost as usual in the ten days before the Japanese attacked. Probably it was chance rather than design that brought all eight battleships of the Pacific Fleet into Pearl Harbor at one time on and after 2 December. At any rate they made a fine showing for the newly appointed Soviet Ambassador to the United States, Maxim Litvinoff, who arrived from the Orient enroute to the United States on Thursday afternoon, 4 December-and became an unofficial overnight guest of the Governor and his naval aide.  The three most valuable properties of the Pacific Fleet, the aircraft carriers Lexington, Enterprise, and Saratoga, were all away. The battleship crews undoubtedly provided many of the 24,000 spectators who witnessed the annual Shrine-sponsored football game on Saturday afternoon, 6 December, from which the University of Hawaii emerged victorious over Willamette University by a score of 20 to 6.

Three days earlier, a plea for more field repair and maintenance equipment had been sent by the Hickman commander to the Commanding General, Hawaiian Air Force, which opened: “Due to the unsettled world conditions, it is believed that there is a probability of there being a necessity in the near future of repairing and defending this and other airdromes of this Department.”  But the official Army outlook, as presented in a reconstructed G-2 estimate of the situation, was less alarming. This estimate noted that the Hawaiian Department had no knowledge of Japanese naval vessels in waters farther east than the China Sea and no information to indicate operations by Japanese aircraft except on the Asiatic mainland and in adjacent areas. Locally, there had been plenty of warnings about sabotage, but no action by a resident of the Territory of Hawaii had indicated that subversive acts would be committed. The conclusions were:

  1. There was a possibility that disruption of relations, or war might result at any time from overt acts by Japan either in the form of military action in the Far East, sinking of transports en route to the Philippines, or other similar acts.
  2. With the large part of the American Navy based in the Hawaiian waters the probability of an attack by the Japanese carriers was believed to be negligible.

In other words Hawaii, preparing for war, as, yet had no need itself to be ready for large-scale attack.

The Plan and Launching of the Attack

The Japanese Navy had a very different idea, although the surprise carrier attack on Oahu on the morning of 7 December 1941 did not become an integral part of Japanese war plans until almost the last moment. For several years before 1941, Japanese naval plans had contemplated a possible submarine attack on the United States Fleet in Hawaiian waters, but it was only in January of that year that a scheme was proposed for a surprise air attack on the fleet while berthed and anchored in Pearl Harbor. Japanese sources are unanimous in crediting authorship of the idea to Admiral Isoroku Yamamoto, commander in chief of the Combined Fleet. Its feasibility may have been suggested by United States Fleet exercises of 1938, during which the carrier Saratoga demonstrated that such a surprise attack could be successfully launched. Yamamoto’s proposal, and its subsequent highly secret study, coincided with a rumor reported by Ambassador Joseph C. Grew from Tokyo on 27 January 1941 that a surprise mass attack on Pearl Harbor was being planned by the Japanese.

In May 1941 Admiral Yamamoto presented his idea to the Japanese Naval General Staff. Without rejecting it outright that body remained, at least until late August, generally opposed to including a risky carrier operation in Japanese plans for naval action in the event of war with the United States; and it was not until 20 October that the Naval General Staff formally approved the plan. In the meantime, it appears that during the spring and summer of 1941 the 1st Air Fleet under Yamamoto’s direction undertook some preliminary detailed planning and training for an attack such as the admiral had projected; and between 2 and 13 September his plan was war-gamed in Tokyo by Combined Fleet and Naval General Staff officers. In the midst of these table-top maneuvers, on 6 September, the Japanese Government made its decision to go to war with the United States, Great Britain, and the Netherlands, unless it’s minimum demands for control of a Greater East Asia Co-Prosperity Sphere were met by late October.

War-gaming convinced the Japanese Navy that the Pearl Harbor plan was feasible, although it might cost two carriers and one-third the attacking force of planes. Some serious technical difficulties remained to be overcome: one was the problem of a mid-Pacific mass refueling; another, not solved until early October, involved fixing wooden fins to naval torpedoes in order to stabilize them enough to be effective in the shallow waters of Pearl Harbor; another required the last-minute conversion of a large number of 16-inch armor-piercing shells into 1,760-pound aerial bombs for the high altitude horizontal bombers to be employed. In late October the project was allotted top priority and maximum strength when the Japanese Army agreed to release aircraft from Manchuria for southern operations, and six carriers-including two new ones just commissioned-became available for the Hawaiian attack, instead of four as previously planned. On 5 November the Japanese Navy issued its detailed operational orders for action, on 7 November it tentatively announced 8 December (7 December in Hawaii) as “opening day,” and by 17 November the approved detailed plan for the Pearl Harbor attack had been delivered to the Striking Force. Sailing from a desolate harbor in the Kurils on 27 November, its ships moved silently and undetected across the North Pacific, but with orders to return if the United States and Japan reached agreement before the fatal day.

The Carrier Striking Task Force, or 1st Air Fleet, that was headed for Oahu, was a power-packed combination of 6 fast carriers supported and escorted by 2 fast battleships, 2 heavy cruisers, 6 destroyers, and 3 submarines. Aboard the carriers were more than 360 airplanes. Information passed through Tokyo kept the Striking Force supplied with precise last-minute information about the ships actually in Pearl Harbor, although the maps and some of the information available to the force were distinctly out of date. After reaching a point 500 miles due north of Oahu during the evening of 6 December (Hawaiian dating), the ships raced southward and prepared their planes for launching at a point about 200 miles from the island.

In the meantime another Japanese force of twenty-five submarines had deployed south of Oahu. These long-range and modern submarines belonged to the Advance Expeditionary Force of the 6th Fleet, and five of them carried two-man midget submarines “piggy-back,” for launching and penetration of Pearl Harbor to abet the air attack. And, if the Pacific Fleet got wind of the approaching carrier force and sortied, the 6th Fleet submarines were to attack en masse.

The Japanese planned to fly the first wave of planes from the carriers at 6:00 a.m. and begin their bombing two hours later, one-half hour after the United States had been formally notified by Japan that it would seek recourse to arms to attain its ends. Thus did Japan plan to avoid a charge of “attack without warning,” but the plan cut the time element too fine to allow for human error (in this case, slow decoding and typing of the Japanese message at the Washington Embassy) and the bombs were falling before Japanese diplomats arrived at the State Department to deliver the news of war. From intercepts American officials had already obtained a full translation of the Japanese message hours earlier, but they did not appreciate the full significance of its 1:00 p.m. deadline (7:30 a.m., Oahu time). Even General Marshall, who sent a last-minute warning about the deadline to Pacific commanders, went home to lunch instead of waiting in his office to find out what might be going to happen at that hour. And his warning did not reach General Short until hours after the event.

On Oahu the military forces did obtain other warnings of impending action. More than four hours before the air attack began, one of the midget submarines was sighted less than two miles outside the Pearl Harbor entrance buoy, and either this submarine or another like it was sunk near the harbor entrance at a quarter to seven. According to standing orders, the presence of any unidentified submarine in restricted waters was to be considered a warning of imminent attack on a larger scale; but the Navy was still in process of checking the authenticity of reports of these submarine actions when the big attack came. No one thought to tell the Army about them.

On Oahu’s north shore, three Army mobile SCR-270 radar sets were in operation this Sunday morning, from 4:00 to 7:00 a.m., in accordance with the schedule established under Alert No. I. All three (Kawailoa, Opana, and Kaaawa) recorded the approach of two Japanese reconnaissance planes, launched from cruisers, when they were about fifty miles away, beginning at 6:45 a.m. One of the stations (but not Opana) reported this flight to a Navy lieutenant on duty at the Army information center at Fort Shafter about 6:52 a.m., who reported it to another Navy lieutenant who responded that the Navy “had a reconnaissance flight out and that’s what this flight was.” Much better known is the report by the Opana station at 7:20 a.m. of a mass flight of planes approaching from a northerly direction. This was the first wave of Japanese bombers and fighters, which had been spotted by the Opana radar just after seven while still some 130 miles from Oahu. By the time the Opana report came in the information center had officially closed down, and an Army lieutenant who happened to be still on duty decided that nothing need be done about the call-he knew that American carriers were out and assumed that Opana had picked up a reconnaissance flight from one of them.

The Attack and the Response

An exact account of the Japanese air attack on the Pearl Harbor area and on Army airfields elsewhere on Oahu is impossible, partly because the commander of the first wave of planes gave a signal that was partially misinterpreted, so that the action did not proceed exactly according to a calculated plan. The first wave consisted of 49 high-level bombers, 51 dive bombers, 43 fighters, and 40 torpedo planes, a total of 183 planes. After approaching the north shore of Oahu about 7:40 a.m., some of the planes circled the island in order to swing in from the sea against south shore targets, while others flew over and between the mountain ranges to attack Wheeler Field and then other targets beyond. The attack began in the Pearl Harbor area at 7:55 a.m.-or five minutes early by the schedule so nicely timed in relation to the Japanese notification to Washington. All types of Japanese planes attacked more or less simultaneously. The torpedo planes did the greatest havoc to the battleships and other naval vessels afloat. Altogether, 8 battleships, 3 light cruisers, 3 destroyers, and 4 other naval vessels were destroyed or severely damaged, and most of this damage was done by the first wave. The greatest loss of life (almost half the total occurred early in the attack after one of the converted 16-inch shell bombs crashed into the battleship Arizona and exploded in a forward magazine, with awesome consequences. Within five minutes or so the Navy’s ships, whether hit or not, began putting up a tremendous antiaircraft barrage. The ships had 353 large-caliber and 427 short-range weapons aboard-or several times the Army’s antiaircraft strength on Oahu. Nonetheless, while many Japanese planes were riddled, only 9 were lost from the first wave as a result of American combat action.

The second wave of Japanese planes consisted of 54 high-level and 80 dive bombers and 36 fighters, making the total number of Japanese planes participating in the attack 353, plus the 2 reconnaissance planes that came in earlier. Launched one hour and fifteen minutes after the first wave, the planes of the second began to arrive on target shortly before 9:00 a.m. and continued the mass attack until about 9:45. The second wave, meeting stiffer antiaircraft resistance (mostly from Navy guns) and from a few Army fighter planes, lost 20 planes in action. The loss in combat of 29 planes represented 8 percent of those engaged, a proportion close to the average loss then being sustained by attacking forces in similar-sized air raids in Europe against alerted defenses. Some other Japanese planes were smashed up as they returned to their carriers, and of these at least 20 were a total loss. By about 1: 00 p.m. all returning Japanese planes were back on the carriers, and the Striking Force raced away to the northwest.

Although damage to the Pacific Fleet was the primary objective, the Japanese assigned 199 of the attacking planes, or nearly 60 percent of the total force, to missions against Army and Navy airfields on Oahu. The results for the Navy and the Marine Corps on this account were even more devastating than for the Army: at the Kaneohe Seaplane Base on the northeast shore, every one of the 33 patrol planes present was destroyed or damaged; nearly as great loss was sustained at the Ewa Marine Air Station west of Pearl Harbor, where not a single plane was left in condition to fly during or immediately after the attack; and the same fate overtook all of the patrol planes at the Ford Island Naval Air Station. In all, the Navy and Marine Corps had 87 planes destroyed and 31 damaged, and these figures included almost all of the fighters, bombers, and patrol planes on hand. In addition, during and after the attack the carrier Enterprise lost a number of planes flown into the battle area, at least five of which were shot down by naval antiaircraft fire.

At Hickam Field, where the Army had its usable bombers lined up in close formation in front of the hangars, the first Japanese planes flew over at 7:55 a.m. These were torpedo planes headed for Pearl Harbor, but they were followed almost immediately by four flights of dive bombers coming in from the south, southeast, and north almost simultaneously for bombing and strafing attacks on the supply depot, repair shops, and hangars. This opening attack lasted about ten minutes. A second one came at 8:25, this time from more low-flying dive bombers and one or more flights of high-altitude bombers. The third and final attack, by dive bombers and strafing fighters of the second wave, struck around 9:00 a.m. These strikes left the Hawaiian Air Depot completely destroyed, three of the five hangars burned, the barracks and other post installations badly damaged, and more than half the bombers present destroyed or damaged seriously. Casualties at Hickam were also heavy, particularly among men who had taken refuge in the hangars after the first attack. But the most vital facilities-the repair shops and machinery, and gasoline storage tanks-remained largely untouched.

In the midst of the Hickam action twelve unarmed B-17’s being ferried from the mainland arrived over Oahu. Eight of them managed to land at Hickam, and of the other four two came down at Haleiwa, one at Bellows, and one on a golf course near the northern tip of Oahu. Enemy action destroyed one of the planes and badly damaged three others.

A few minutes after the initial attack on Hickam, about twenty-five dive bombers hit at the hangars at Wheeler Field, and heavy casualties occurred when one bomb exploded in an adjoining barracks. After the bombing, the Japanese planes circled back at very low altitudes to machine-gun the pursuit craft parked (as at Hickam) in close formation in front of the hangars, and, as they circled, some of the enemy strafed nearby Schofield Barracks. After an extended lull another machine gun attack struck Wheeler, shortly after 9:00 a.m., and caught a number of pursuit ships being taxied to the runways for launching. Wheeler lost two hangars, and more than two-thirds of its planes were destroyed or badly damaged. The first attack effectively prevented any large-scale response by Wheeler’s fighter planes.

On the eve of Pearl Harbor the Army had two of its pursuit squadrons dispersed to Bellows and Haleiwa Fields for gunnery practice, and the planes of these squadrons were armed and needed only fuel and warming up to be ready for action. Apparently the Japanese did not plan to attack either of these outlying fields. A single fighter strafed Bellows about 8:30 a.m., and the flight of nine planes that attacked the same field about a half-hour later seems to have been attracted by the B-17 which landed there. Material damage at Bellows was slight, and was even less at Haleiwa Field, strafed by a single plane that followed in the two B-17’s which landed there. The second attack on Bellows caught the Army pursuits just as they were taking off. Two of them were shot down before they could gain altitude, and one pilot was killed as he climbed into his plane.

At all Army installations attacked by the Japanese, enemy dive bombers and fighters strafed individuals promiscuously, and in return Army men fired back with machine guns and lesser weapons. But the only effective action came from the planes at Haleiwa. Two young lieutenants at Wheeler were sufficiently alert after an all-night poker game to phone Haleiwa to have their planes fueled and warmed up and then to race over there and get off in P-40’s at or soon after 8:15 a.m. One of them is credited with shooting down four Japanese planes. Another flight from Haleiwa had a less happy result when one of its planes, a P-36, was shot down by machine-gun fire from Schofield Barracks. Six P-36’s managed to get into the air from Wheeler Field during the attack, and four of them engaged the nine enemy planes which attacked Bellows Field. American pilots claimed two of the Japanese, and one of their own number was shot down.

Including the B-17’s arriving from the mainland, some 249 Army planes were involved in the Pearl Harbor attack, and of these about 74 were destroyed and 71 seriously damaged. Among bombers the B-18’s, which were expendable, sustained the greatest loss; 14 of 24 B-17 heavies and 10 of 12 modern light A-20 bombers came through comparatively unscathed. The fighters took a heavier beating, but by 10 December the Army had 44 of them ready for action.

Most of the Army’s antiaircraft guns were unable to function during the attack. None of the mobile 3-inch batteries was at its assigned field position, and ammunition for all of them had to be fetched from the Ordnance Depot. The Hawaiian Coast Artillery Command alerted the units of the 53d Coast Artillery Brigade (Antiaircraft Artillery) at 8: 10 a.m., and within three or four minutes antiaircraft batteries at Fort Kamehameha (next to Hickam) and at Fort Weaver (on the other side of the Pearl Harbor entrance) opened fire with small arms. At 8:30 a fixed 3-inch battery at Weaver began to fire, and similar batteries at Kamehameha and on Sand Island in Honolulu harbor opened up against Japanese planes, the Sand Island battery claiming two of them. Other antiaircraft units at Camp Molekoli and Schofield Barracks fired small arms only at the enemy, the Schofield unit claiming one plane (in addition to the American one). But, with only a small fraction of the Army’s antiaircraft potential brought into play, its effort on this score was insignificant in comparison with the barrage thrown up by the guns of the Pacific Fleet.

Within minutes after the first torpedoes and bombs struck at Pearl Harbor, General Short issued orders that put the Hawaiian Department on a full war footing. By 8:45 a.m. his headquarters had begun to operate a forward command post located in tunnels at the Aliamanu Crater, three miles west of Fort Shafter. Between 8:20 and 9:00 a.m. the major ground commands-the Hawaiian Coast Artillery Command and the 24th and 25th Infantry Divisions-received word to deploy and take the actions required under a No. 3 Alert. Actually, all three had begun so to act before they got the formal word. The 24th Division had a battalion of infantry on the road from Schofield Barracks to its assigned battle position by 9:00 a.m., and thereafter other divisional units left Schofield as soon as they had drawn and loaded their ammunition and otherwise prepared for action. By late afternoon, all divisional elements were digging in at their assigned field positions, with all weapons except heavy howitzers at hand and ready to fire. As General Short put it, in the deployment “everything clicked,” one of his junior officers explaining: “We had gone so many times to our war positions that it just seemed like drill when they were firing at us.” The deployment showed clearly enough that the Hawaiian Department was thoroughly prepared to resist invasion, however unready it was against the peril of surprise air attack.

After the attack was over the Army defenders, still anticipating invasion, gave credence to a host of rumors and reports that enemy forces were still at hand. Throughout 7 December reports that parachute troops had landed poured in from all over Oahu, and sightings of hostile ships off shore were almost as numerous. With darkness the situation became even more tense, and General Short ordered all forces to be ready to resist another air attack or attempted landing at dawn. Throughout the night Army troops fired small weapons rather freely all over the island-with some ground patrols firing at each other. The following entries from the War Diary of the Hawaiian Coast Artillery Command for 8 December indicate the tension as the new dawn approached:

0428-All units notified to be on alert for landing attack at dawn.

0438-Flash. 30 Enemy planes approaching from Kauai.

0507-Enemy planes dive bombing Wheeler Field. (Some firing by batteries in Wheeler Field took place.)

0525-Schofield AA group reports barrage fire (searchlights useless because of low ceiling) against planes, later reported as friendly.

0608-53d Brigade reports small arms firing on friendly aircraft definitely established as from Marines or Navy.

By afternoon on 8 December a more normal outlook began to prevail. During the second night the firing tapered off, and orders similar to the following, issued by the commander of the 25th Division, helped to stop it: Promiscuous firing at friendly airplanes has been prevalent during preceding 36 hour period. Such firing will be stopped at once. Under no circumstances will any person in this division take up fire against any airplanes hostile or friendly until he or his unit has been definitely attacked by bombing or machine gun fire. The last stray planes of the enemy had in fact departed from their rendezvous point west of Oahu about 11:00 a.m. on the morning of 7 December, although enemy submarines were still around.

Except for some strafing, the Japanese confined their attack on 7 December to military installations. The “bombs” which fell on Honolulu and other civilian parts of the island were Navy 5-inch antiaircraft shells which had failed to detonate in the air. Explosions in Honolulu started three major fires, and at least 57 civilians were killed and nearly as many seriously injured.

Casualties among American service personnel were of course much higher. The Navy and Marine Corps have counted 2,117 killed or died of wounds, and 779 others wounded in action.  The far smaller Army casualties are difficult to determine with exactitude. General Short, in his report on the battle, listed 228 Army men dead or died of wounds, 110 seriously wounded, and 358 slightly wounded, a total of 696 Army battle casualties, as of midnight, 10 December. These appear to be about as accurate as any figures compiled and published since. The enemy acknowledged a loss of 55 men in planes; 9 of the 10 men aboard midget submarines were lost, the other one being America’s first prisoner of war in World War II; and on 10 December the Japanese also lost one of their large submarines (the I-70) and its crew.

When General Short submitted his report of the action to the War Department on 12 December, he had not yet heard of the drama being acted out on the isolated island of Niihau, west of Kauai. A crippled Japanese plane landed on Niihau on Sunday afternoon, about 2:00 p.m. After first being disarmed by a native Hawaiian, the Japanese pilot persuaded one of the two men of Japanese descent on the island-an American citizen-to free him, return his weapons, and join him on a rampage. The affair ended on Saturday morning, 13 December, and before help summoned from Kauai had arrived. Another Hawaiian, Benhakaka Kanahele, and his wife were captured by the two Japanese; but they jumped their captors and, after Kanahele was fully aroused by bullets in his stomach, groin, and leg, he picked up the Japanese pilot and smashed his head against a stone wall. The Nisei took one look, shot himself, and the “Battle of Niihau” was over.

Investigation and Judgment

News of the Japanese attack on Oahu reached Washington almost immediately. The Navy sent the first official word at 8:00 a.m., and Secretary Hull knew about the attack before he received the Japanese envoys with their fateful message. President Roosevelt and his principal advisers had expected war, but they were as surprised as the Hawaiian commanders when the war began in Hawaii. To find out what had happened, and why, the President sent Secretary of the Navy Frank Knox on a flying trip to Hawaii, the Secretary arriving there on the morning of 11 December and departing the next afternoon. His report, delivered to Mr. Roosevelt on the morning of 15 December, touched off the first of the formal investigations of the Pearl Harbor attack. None of them developed the position of the Hawaiian commanders any better than Secretary Knox did in his report:

There was no attempt by either Admiral Kimmel or General Short to alibi the lack of a state of readiness for the air attack. Both admitted they did not expect it, and had taken no adequate measures to meet one if it came. Both Kimmel and Short evidently regarded an air attack as extremely unlikely because of the great distance which the Japs would have to travel to make the attack and the consequent exposure of such a task force to the superior gun power of the American fleet. Neither the Army nor the Navy Commander expected that an attack would be made by the Japanese while negotiations were still proceeding in Washington. Both felt that if any surprise attack was attempted it would be made in the Far East.

There was likewise plenty of evidence of what happened on 7 December to substantiate Mr. Knox’s conclusion that “once action was joined the courage, determination, and the resourcefulness of the armed services and of the civilian employees left nothing to be desired.

Despite the devastation wrought by the Japanese, service chiefs both in Washington and in Hawaii underestimated the weight of the Japanese attack. The consensus in the days immediately following the action was that Japan had used no more than three carriers and 180 planes. This under­estimate persisted during December and January through the investigation of the commission headed by justice Owen J. Roberts of the Supreme Court, and it lent a good deal more color than justifiable to charges that the Hawaiian Department could have put up a much more effective defense if its forces had been properly alerted. Undoubtedly, if there had been plenty of warning, there could and would have been a more effective defense, but the Japanese struck with such overwhelming force that there would have been little difference in the damage done-except, of course, to Japanese planes and possibly to the carriers. Certainly the unheeded warnings of the last hour or so before the attack could have made little difference in the Army’s defense. It would have required (and actually did require) several hours’ effort to get most of the Army’s antiaircraft guns into position and ready to fire, and in any event the Army had very few guns that could have dealt with the low-flying torpedo planes and dive bombers. As for the Army’s pursuit ships, the well-known warning by the Opana radar might have provided enough time to disperse them to bunkers at Wheeler Field, but not enough to get them into the air against the first wave of Japanese planes. As Admiral King observed three years after the event, the basic reason the attack succeeded so well was the general blindness of the United States Army and Navy to Japanese potentialities in the central Pacific. The Roberts Commission and later investigations found much to criticize about the organization and operation of defense forces in Hawaii, but General Short and his Navy colleagues stoutly defended the “system.” Said General Short: “I think the system is all right. I think that we made a very serious mistake when we didn’t go to an alert against an all-out attack. I think that our system was perfectly all right. Our estimate of the situation was not.”

Whether Washington gave the Hawaiian commanders enough information to make a correct estimate of the situation remains a much argued question. But on the central issue of responsibility, no one has improved on the judgment of Secretary of War Stimson, recorded in his diary the day that the report of the Roberts Commission was made public:

The printed report does not and could not go into what is the real underlying basis of the trouble, namely, that both services had not fully learned the lessons of the development of air power in respect to the defense of a navy and of a naval base. This failure and shortcoming pervaded the services and the nation. We had grown to rely on the impregnability of Pearl Harbor and nobody had anticipated that the Japs could make an attack by air as thoroughly as they did. Crete and Greece had taught us the vulnerability of a fleet in narrow seas against attacks by shore-based aircraft. It was the Japs who carried out this lesson of attacks upon a fleet from carriers in the high seas. I doubt if anybody in the Navy or the Army believed that they could successfully do it or would try it. Certainly nobody in the responsible positions. And it was only through such a disaster that we could all in the nation learn what modern air power can do even in the high seas.

SOURCE: Guarding the United States And Its Outposts; BY: Stetson Conn, Rose C. Engelman, Byron Fairchild (United States Army Center of Military History)

Pearl Harbor Planning (Jan.-Nov. 1941)

When Japanese planes struck immobile United States warships and aircraft at Pearl Harbor on 8 December 1941, they were executing pinpointed plans conceived months in advance and cloaked in the utmost secrecy. Authoritative Japanese documents obtained since the termination of war and interrogations of the high naval personnel who participated in or had knowledge of this planning make it possible to reconstruct a complete and accurate picture of how the Pearl Harbor attack was conceived and developed over an eight-month period preceding the final outbreak of hostilities.

Prior to 1941 Japanese naval planning for a possible war with the United States had been based upon the assumption that the latter would be Japan’s only enemy and it envisaged awaiting attack by the American fleet in the Western Pacific where Japan’s numerically inferior fleet could operate at an advantage. By the end of 1940, however, Japan’s entry into the Tripartite Alliance and the United States’ aid commitments to Britain had created a new international line-up which made previous Japanese naval planning obsolete. The Japanese Navy began to plan for a simultaneous war against the United States and Britain.

The idea of a surprise attack on Pearl Harbor at the outset of war, with the object of gaining at least temporary naval supremacy in the Western Pacific, was first conceived in early January 1941 by Admiral Yamamoto, Commander-in-Chief of the Japanese Combined Fleet. Admiral Yamamoto at that time ordered Rear Admiral Takijiro Onishi, chief of staff of the Eleventh Air Fleet, to study the feasibility of such an attack.

On the basis of this preliminary study, Admiral Yamamoto in June 1941 began actively pressing for the adoption of his plan by the Navy General Staff as part of Japan’s naval strategy in the event of war. Crippling the United States fleet at Hawaii at the start of hostilities, he argued, was absolutely essential to place the Western Pacific under Japanese control for the period necessary to complete the occupation of the strategic areas and economic resources of the South. Were American fleet strength at Hawaii left intact, it could immediately make an incursion into the Western Pacific in the midst of the Southern operations, catching the Japanese fleet dispersed in different areas and unable to deploy for a decisive battle. Under these conditions, he warned, the United States would probably seize Japan’s island bases in the Marshals and transform them into advance bases of operation against Japan.

Despite Admiral Yamamoto’s arguments, his plan was vigorously opposed by a section of the Navy General Staff on the ground that swift occupation of the Southern areas was the prime necessity, and that this might fail if Japanese naval strength were divided between operations against Hawaii and support of the Southern invasions. It was further pointed out that detection of the Japanese force en route to Hawaii might result in its complete destruction, and that, even if this did not occur, the attack would be ineffectual if the bulk of the United States fleet was not caught in Pearl Harbor.

This disagreement in the Navy High Command had not been resolved by 10 September, when staff officers of all fleet units assembled at the Naval War College in Tokyo for the annual Navy war games. Just four days earlier the Imperial conference of 6 September had debated the issue of war or peace in a dramatic session and had decided that Japanese military preparations must be speedily brought to completion. The games therefore took place amidst an atmosphere of unusual tension, further heightened by the fact that the central problem of study assumed an American fleet attack into the Western Pacific as a result of Japanese invasion operations in the Southern area.

Admiral Yamamoto himself planned and exercised over-all supervision of the games. A general study session, including chart maneuvers participated in by all officers in tactical command of fleet units, occupied the first three days–10, 11, and 12 September. The last day, 13 September, was devoted to a special study session. Thirteen umpires headed by Rear Adm. Seiichi Ito, Vice-Chief of Navy General Staff, ruled on the execution of maneuvers. The Japanese (Blue) Forces were under command of Rear Admiral Matomi Ugaki, Chief of Staff of the Combined Fleet, and the British-American (Red) Forces under command of Vice Admiral Shiro Takasu, First Fleet Commander.

While the principal games were conducted on the old hypothesis of meeting an American fleet attack in the Western Pacific, a restricted group of staff officers of the Combined Fleet and commanders of those fleet units which eventually made up the Pearl Harbor Task Force met in a separate and top-secret session, the purpose of which was to study problems connected with a possible surprise attack on Pearl Harbor. These problems included:

1. Feasibility of an attack if (as estimated) only 50 per cent of American Pacific Fleet strength were in harbor.

2. The possibility of detection by American search planes before the attack could be executed.

3. The refueling at sea of Task Force units with inadequate cruising range.

The conclusions reached with regard to the solution of these problems were those later embodied in the actual operational plan and carried out in the Task Force attack. However, it was not until 20 October, after Admiral Yamamoto had threatened to resign over the issue, that Admiral Osami Nagano, Chief of Navy General Staff, approved the Pearl Harbor plan in principle over General Staff opposition. Preparation of the detailed attack plan was completed during October and finally sanctioned by Admiral Nagano on 3 November. In order to preserve secrecy, knowledge of the plan in its entirety was limited to the Chief and Vice-Chief of the Navy General Staff, the Chief and members of the Operations Section, Navy General Staff, Commander-in­Chief, Chief of Staff, and most staff officers of the Combined Fleet, First Air Fleet and Sixth Fleet. Evidence indicates that Army leaders were not informed until sometime in November, following the issue of Combined Fleet Top Secret Operations Order No. 1.

Even in this order, issued on 5 November, the missions of the Advance (Submarine) Force and the Task Force which were to participate in the Pearl Harbor attack were left blank in the printed text, and the missing portions were communicated verbally only to those listed in the preceding paragraph. The commanders of the Task Force units, which assembled in Tankan Bay between 15 and 22 November, were not informed of the attack plan until Vice Admiral Nagumo, commanding the Force, issued Task Force Top Secret Operations Order No. 1 on 23 November, three days before departure for Hawaiian waters. Crew members were told that Pearl Harbor was the target only after receipt of the Combined Fleet X-Day order on 2 December.

{CONTRIBUTOR NOTE: the date 8 December for the attack is due to the International Date line, it was this date in Tokyo}


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